Force me, every now and then, to let go (4)
I believe the answer is:
free
'let go' is the definition.
(I've seen this in another clue)
'force me every now and then' is the wordplay.
'every now and then' means one should take alternating letters (letters selected at regular intervals).
'force'+'me'='forceme'
The alternating letters of 'forceme' are 'FREE'.
'to' acts as a link.
(Other definitions for free that I've seen before include "Reef (anag.)" , "Gratis, for nothing" , "Not employed" , "Untie" , "Unrestrained" .)