Edge on front of bowler -- that's it! (4)
I believe the answer is:
brim
'edge' is the definition.
(I know that brim is a type of edge)
'front of bowler that's it' is the wordplay.
'front of' suggests taking the first letters.
'that's it' becomes 'rim' (I am not sure about this - if you are sure you should believe this answer much more).
The first letter of 'bowler' is 'b'.
'b'+'rim'='BRIM'
'on' acts as a link.
Can you help me to learn more?
(Other definitions for brim that I've seen before include "Peak (of cap); be very full" , "Topmost edge" , "Circumference" , "Top edge of cup etc" , "Upper edge" .)