Pleased with a grand fellow (4)
I believe the answer is:
glad
'pleased with' is the definition.
(thesaurus)
'a grand fellow' is the wordplay.
'a grand' becomes 'g' ('G' can be a synonym of 'grand').
'fellow' becomes 'lad' ('lad' can be a synonym of 'fellow').
'g'+'lad'='GLAD'
(Other definitions for glad that I've seen before include "Informal flower < -girl" , "More than willing" , "part of Iris's family" , "Made up" , "Contented" .)