Brooded quietly at home, cutting grass (7)
I believe the answer is:
repined
'brooded' is the definition.
(both can mean to think unhappily about something)
'quietly at home cutting grass' is the wordplay.
'quietly' becomes 'p' (p for piano and quiet).
'at home' becomes 'in' (similar in meaning).
'cutting' is an insertion indicator (some letters cut their way into a word).
'grass' becomes 'reed' (I've seen this before).
'p'+'in'='pin'
'pin' going inside 'reed' is 'REPINED'.
(Other definitions for repined that I've seen before include "Fretted; was discontented" , "Expressed discontent" , "Languished" , "Grudged" , "Regretted" .)