At home, wearing hairpiece, having second thoughts (5)
I believe the answer is:
ruing
'having second thoughts' is the definition.
(to rue something is to regret it)
'at home wearing hairpiece' is the wordplay.
'at home' becomes 'in' ('I'm in' can mean 'I'm at home').
'wearing' indicates putting letters inside.
'hairpiece' becomes 'rug' (rug is a kind of hairpiece).
'in' inserted inside 'rug' is 'RUING'.
(Other definitions for ruing that I've seen before include "Feeling sorry for" , "Regretful" , "feeling remorse" , "Feeling bad" , "Having second thoughts" .)