Lovers at it frenetically, increasingly under covers (8)
I believe the answer is:
amoretti
'lovers at' is the definition.
The definition suggests a singular noun which matches the answer.
'it frenetically increasingly under covers' is the wordplay.
'frenetically' is an anagram indicator (I've seen this in other clues).
'increasingly under' becomes 'amoret' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'covers' is a charade indicator (letters next to each other).
'it' anagrammed gives 'ti'.
'ti' put after 'amoret' is 'AMORETTI'.
Can you help me to learn more?
(Other definitions for amoretti that I've seen before include "Bonkers" , "images of Cupid" , "Plump lads" , "Pretty artistic boys" , "Little winged creatures" .)