The most common and most likely answer to this crossword clue is the 2 letter word FO
I've seen this crossword clue in The Times
F
O
Buddy explains!

The straight part
We know that "platform" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case platform = fo.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does FO mean?
FO noun- A leaf of a book or manuscript
- A page of a book, that is, one side of a leaf of a book.
- A page number. The even folios are on the left-hand pages and the odd folios on the right-hand pages.
- A sheet of paper folded in half.
- (books) A book made of sheets of paper each folded in half (two leaves or four pages to the sheet); hence, a book of the largest kind, exceeding 30 cm in height.
- A page in an account book; sometimes, two opposite pages bearing the same serial number.
- (19th to early 20th century) A leaf containing a certain number of words; hence, a certain number of words in a writing, as in England, in law proceedings 72, and in chancery, 90; in New York, 100 words.
- A wrapper for loose papers.
- Pronunciation spelling of four.
- Towards; in the direction of.
- Directed at; intended to belong to.
- In order to help, benefit, gratify, honor etc. (someone or something).
- To be used or treated in a stated way, or with a stated purpose.
- Supporting, in favour of.
- Because of.
- Intended to cure, remove or counteract; in order to cure, remove or counteract.
- Over (a period of time).
- Throughout or across (a distance in space).
- Used to introduce a subject within a to-infinitive clause.
- On behalf of.
- In the role or capacity of; instead of; in place of.
- In exchange for; in correspondence or equivalence with.
- In order to obtain or acquire.
- By the standards of, usually with the implication of those standards being lower than one might otherwise expect.
- To be, or as being.
- (usually in the phrase 'for all') Despite, in spite of.
- Indicating something desired or anticipated.
- (in expressions such as 'for a start') Introducing the first item(s) in a potential sequence.
- (with names) In honor of; after.
- Due or facing (a certain outcome or fate).
- Out of; used to indicate a fraction, a ratio
- Used as part of a score to indicate the number of wickets that have fallen.
- Indicating that in prevention of which, or through fear of which, anything is done.
- Used in various more-or-less idiomatic ways to construe individual verbs, indicating various semantic relationships such as target, purpose, result, etc.; see also the entries for individual phrasal verbs, e.g. ask for, look for, stand for, etc.