Tolerate fellows throwing ruse out (6)
I believe the answer is:
suffer
'tolerate' is the definition.
(I know that tolerate can be written as suffer)
'fellows throwing ruse out' is the wordplay.
'fellows' becomes 'ff' (an abbreviation for fellow written twice).
'throwing' indicates anagramming the letters (letters get thrown around).
'out' is an insertion indicator.
'ruse' is an anagram of 'suer'.
'ff' going within 'suer' is 'SUFFER'.
(Other definitions for suffer that I've seen before include "Experience (something bad)" , "Endure pain or discomfort" , "Endure; hurt" , "Feel pain" , "Experience hurt" .)