New mascot hard to put up with (7)
I believe the answer is:
stomach
'put up with' is the definition.
(synonyms)
'new mascot hard' is the wordplay.
'new' indicates an anagram.
'hard' becomes 'h' (abbreviation used in pencil classifications).
'mascot' with letters rearranged gives 'stomac'.
'stomac'+'h'='STOMACH'
'to' is the link.
(Other definitions for stomach that I've seen before include "Endure; organ" , "Mac hosts his organ" , "Tummy" , "Saclike organ" , "Appetite for food" .)