Fool that's got a good grip? (6)
I believe the answer is:
sucker
I believe this clue is a double definition.
'fool' is the first definition.
(synonyms)
'that's got a good grip?' is the second definition.
(eg an octopus' sucker is good at gripping)
(Other definitions for sucker that I've seen before include "Fool" , "with straw in mouth?" , "Shoot coming from roots, or slangy victim" , "baby?" , "Slangily, one who is easily deceived" .)