More generous thief, perhaps, shelling out grand (5)
I believe the answer is:
nicer
'more generous' is the definition.
'thief perhaps shelling out grand' is the wordplay.
'thief perhaps' becomes 'nicker'.
'shelling out' is a deletion indicator.
'grand' becomes 'k' ('K' can be a synonym of 'grand').
'nicker' with 'k' taken out is 'NICER'.
(Other definitions for nicer that I've seen before include "better" , "More pleasant, French resort close to Montpellier" , "More pleasant or courteous" , "Kinder; finer" , "more likeable" .)