Find a couple of letters tucked in behind the clock (6)
I believe the answer is:
locate
'find' is the definition.
(I know that locate is a type of find)
'a couple of letters tucked in behind the clock' is the wordplay.
'a couple of letters' can mean two replacements for 'letter'.
'letter' becomes 'o'.
'letter' becomes 'c'.
'tucked in' indicates putting letters inside (I've seen this in other clues).
'behind the clock' becomes 'late' (I've seen this in another clue).
'o'+'c'='oc'
'oc' placed inside 'late' is 'LOCATE'.
(Other definitions for locate that I've seen before include "Lay one's hands on (something)" , "Place, situate" , "Track down" , "Discover the exact position of" , "Fix position of" .)