General flying in balloon (7)
I believe the answer is:
enlarge
'balloon' is the definition.
(thesaurus)
'general flying' is the wordplay.
'flying' indicates an anagram.
'general' with letters rearranged gives 'ENLARGE'.
'in' is the link.
(Other definitions for enlarge that I've seen before include "scale up" , "Expatiate" , "Stretch" , "Blow up" , "Describe in more detail" .)