Confront oarsman making progress in water (12)
I believe the answer is:
breaststroke
'making progress in water' is the definition.
(swimming stroke)
'confront oarsman' is the wordplay.
'confront' becomes 'breast' (breast can mean to face or confront).
'oarsman' becomes 'stroke' (I've seen this before).
'breast'+'stroke'='BREASTSTROKE'
(Other definitions for breaststroke that I've seen before include "Adam Peaty's swimming style" , "What swimmers may do" , "Natant style" .)