Pity -- he nods off in a trance! (10)
I believe the answer is:
hypnotised
'in a trance' is the definition.
('in a trance'->'hypnotized' is in my internal thesaurus and 'ize'->'ise')
'pity he nods off' is the wordplay.
'off' indicates anagramming the letters.
'pity'+'he'+'nods'='pityhenods'
'pityhenods' is an anagram of 'HYPNOTISED'.
(Other definitions for hypnotised that I've seen before include "Put under" , "in a trance!" , "Mesmerised" .)