Fit to bore? (4)
I believe the answer is:
well
I believe this clue is a double definition.
'fit' is the first definition.
(associated in meaning)
'bore?' is the second definition.
(I've seen this before)
'to' acts as a link.
(Other definitions for well that I've seen before include "boring" , "Pour - thoroughly" , "abundantly" , "Bore; very much" , "Flood - thoroughly" .)