Cricketer with top hat under pressure (4,6)
I believe the answer is:
pace bowler
'cricketer' is the definition.
(I've seen this before)
'top hat under pressure' is the wordplay.
'top' becomes 'ace' (ace can informally mean very good).
'hat' becomes 'bowler' (bowler is a kind of hat).
'under' is a charade indicator (letters next to each other) (below, in a down clue).
'pressure' becomes 'p' (abbreviation).
'ace'+'bowler'='acebowler'
'acebowler' put after 'p' is 'PACE-BOWLER'.
'with' acts as a link.
(Other definitions for pace bowler that I've seen before include "He's quick" , "One quickly delivers" , "Cricketer" .)