The most common and most likely answer to this crossword clue is the 5 letter word RITES
I've seen this crossword clue in Financial Times
R
I
T
E
S
More clues leading to the result RITES
- Is author heard in offices?
- Icons ducking special procedures
- Scripture upheld established practices
- Customs of outspoken authors
- Reportedly puts in order forms
- Pens, we’re told, ceremonial forms
- Reportedly composes ceremonies
- Ceremonies requiring legal freedoms on the radio
- Formal procedures necessary to inherit estate
- Homophonically, corresponds with ‘ceremonies‘
Buddy explains!

The straight part
We know that "Customs" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case customs = rites.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 RITES mean?
RITES noun- That which complies with justice, law or reason.
- A legal, just or moral entitlement.
- The right side or direction.
- The right hand or fist.
- The ensemble of right-wing political parties; political conservatives as a group.
- The outward or most finished surface, as of a coin, piece of cloth, a carpet, etc.
- A wave breaking from right to left (viewed from the shore).
- A religious custom.
- (by extension) A prescribed behavior.