Upset cricketer with small, silly thing? (6)
I believe the answer is:
sledge
'upset cricketer' is the definition.
(sledging means taunting an opposing cricket player)
'with small silly thing?' is the wordplay.
'with' says to put letters next to each other.
'small' becomes 's' (abbreviation - e.g. clothes size).
'silly thing?' becomes 'ledge' (a ledge is similar to a sill).
's'+'ledge' is 'SLEDGE'.
(Other definitions for sledge that I've seen before include "Try rattling opposing players" , "Vehicle for transportation over snow" , "one could go downhill fast" , "Snow conveyance" , "Snow vehicle or heavy hammer" .)