Moderate loses the head frequently? (5)
I believe the answer is:
often
'frequently?' is the definition.
('often' can be a synonym of 'frequently')
'moderate loses the head' is the wordplay.
'moderate' becomes 'soften' (synonyms).
'loses the head' means to remove the first letter (I've seen 'losing the head' mean this).
'soften' with its first letter taken off is 'OFTEN'.
(Other definitions for often that I've seen before include "Turn away" , "Frequently, habitually" , "Frequently, many times" , "on many occasions" , "Repeatedly with regularity" .)