Clock and TV close to mantelpiece? Indeed possible (3,4,2)
I believe the answer is:
set eyes on
'clock' is the definition.
(to clock is to see or notice)
'tv close to mantelpiece? indeed possible' is the wordplay.
'tv' becomes 'set' (I've seen this in other clues).
'close to' suggests the final letters (the 'close' to the word).
'indeed' becomes 'yes' (agreeing).
'possible' becomes 'on' ('not on' can mean unacceptable or not possible).
The last letter of 'mantelpiece' is 'e'.
'set'+'e'+'yes'+'on'='SET EYES ON'
'and' acts as a link.
(Other definitions for set eyes on that I've seen before include "Catch sight of, observe" , "Spot" , "Notice" , "Espy" .)