After central heating I'll cool off (5)
I believe the answer is:
chill
'cool off' is the definition.
(I've seen this before)
'after central heating i'll' is the wordplay.
'after' means one lot of letters go next to another.
'central heating' becomes 'ch'.
'ch'+'ill' is 'CHILL'.
(Other definitions for chill that I've seen before include "Unpleasant coldness in the air" , "Preserve by cold" , "Iciness" , "Make cold (or frightened)" , "Make cold; relax" .)