Stroke worries about rowers' finish (6)
I believe the answer is:
caress
'stroke' is the definition.
('caress' can be a synonym of 'stroke')
'worries about rowers' finish' is the wordplay.
'worries' becomes 'cares' (I've seen this before).
'about' is an insertion indicator.
'finish' indicates one should take the final letters.
The final letter of 'rowers' is 's'.
'cares' going around 's' is 'CARESS'.
(Other definitions for caress that I've seen before include "Scares with loving gesture" , "Expression of affection" , "Embrace with affection" , "Stroke fondly" , "Affectionate stroke" .)