Fancy one compiler concealing a trap (7)
I believe the answer is:
imagine
'fancy' is the definition.
(thesaurus)
'one compiler concealing a trap' is the wordplay.
'one' becomes 'i' (Roman numeral).
'compiler' becomes 'me' (the person who is writing these clues).
'concealing' indicates putting letters inside.
'trap' becomes 'gin' (I've seen this before).
'a'+'gin'='agin'
'me' enclosing 'agin' is 'magine'.
'i'+'magine'='IMAGINE'
(Other definitions for imagine that I've seen before include "Picture, conceive" , "Enigma, I? (anag)" , "Conceive in the mind" , "Conjure up in mind, visualise" , "Suppose; conceive" .)