Heavens - poet’s good for frolicking (10)
I believe the answer is:
skylarking
'frolicking' is the definition.
('skylark' can be a synonym of 'frolic')
'heavens poet's good' is the wordplay.
'heavens' becomes 'sky' (sky is a kind of heavens).
'poet' becomes 'larkin' (Philip Larkin).
'good' becomes 'g' (abbreviation).
'sky'+'larkin'+'g'='SKYLARKING'
'for' acts as a link.
(Other definitions for skylarking that I've seen before include "Frolics" , "Playing pranks" .)