The most common and most likely answer to this crossword clue is the 3 plus 2 letter word RIG UP
I've seen this crossword clue in The Times
R
I
G
U
P
More clues leading to the result RIG UP
- A clue to short lass’s build
- Quickly arrange to phone, but number’s missing
- Hastily construct one before dog comes back after run
- Assemble riding kit first
- Dress circle — not new — situated above
- Manipulate design group, for me nothing's lost
- Erect upright stupas in the middle
- Police officer with 50 per cent of money around to organise things
- d On debut, girl unfortunately appears in split dress
Buddy explains!

The straight part
We know that "build" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case build = rig up.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.