Bobby is gloomy, needing courage (10)
I believe the answer is:
bluebottle
'bobby' is the definition.
(thesaurus)
'gloomy needing courage' is the wordplay.
'gloomy' becomes 'blue' (I've seen this before).
'needing' means one lot of letters go next to another.
'courage' becomes 'bottle' (I've seen this before).
'blue'+'bottle'='BLUEBOTTLE'
'is' acts as a link.
(Other definitions for bluebottle that I've seen before include "Large fly -- wild cornflower" , "member of force" , "Common blowfly" , "Blowfly - policeman" , "Officer" .)