Sense there's agreement among a boat's crew (8)
I believe the answer is:
eyesight
'sense' is the definition.
(sight is a sense)
'agreement among a boat's crew' is the wordplay.
'agreement' becomes 'yes' (saying yes to something).
'among' indicates putting letters inside (inserted letters are placed among others).
'a boat's crew' becomes 'eight' (I can't explain this - if you can you should give a lot more credence to this answer).
'yes' going into 'eight' is 'EYESIGHT'.
'there's' is the link.
Can you help me to learn more?
(Other definitions for eyesight that I've seen before include "Faculty of vision" , "Perceptive faculty" , "Requirement to look" , "Seeing ability" , "Ability to see" .)