Vision certainly found in rowing crew (8)
I believe the answer is:
eyesight
'vision' is the definition.
(eyesight is a kind of vision)
'certainly found in rowing crew' is the wordplay.
'certainly' becomes 'yes' (I've seen this before).
'found in' is an insertion indicator.
'rowing crew' becomes 'eight' (I've seen this before).
'yes' going within 'eight' is 'EYESIGHT'.
(Other definitions for eyesight that I've seen before include "Ability to see" , "What's needed to see" , "quality of viewing" , "Showing sense" , "Seeing faculty" .)