Happen to find compiler black demure clothes (4,2)
I believe the answer is:
come by
'happen to find' is the definition.
(to come by something is to find it)
'compiler black demure clothes' is the wordplay.
'compiler' becomes 'me' (the person who is writing these clues).
'black' becomes 'b' (as in pencil classifications).
'demure' becomes 'coy' (synonyms).
'clothes' is an insertion indicator (some letters clothe or cover others).
'me'+'b'='meb'
'meb' put inside 'coy' is 'COME BY'.
(Other definitions for come by that I've seen before include "Obtain accidentally - visit informally" , "Manage to acquire" , "Manage to obtain" , "Secure" , "pass" .)