Unwillingly involves person I sacked (5,2)
I believe the answer is:
ropes in
'unwillingly involves' is the definition.
(as in roping in someone reluctant to be involved)
'person i sacked' is the wordplay.
'sacked' indicates anagramming the letters.
'person'+'i'='personi'
'personi' anagrammed gives 'ROPES IN'.
(Other definitions for ropes in that I've seen before include "Recruits" , "Gets involved" , "Involves" .)