Force boy to be pleased (4)
I believe the answer is:
glad
'pleased' is the definition.
(similar in meaning)
'force boy' is the wordplay.
'force' becomes 'g' (short for gravity).
'boy' becomes 'lad' (informal term for boy).
'g'+'lad'='GLAD'
'to be' acts as a link.
(Other definitions for glad that I've seen before include "Joyful" , "Pleased, delighted" , "Contented" , "Dressy clothes, informally .... rags" , "part of Iris's family" .)