Crawler's second year chap not partying (9)
I believe the answer is:
sycophant
'crawler's' is the definition.
(synonyms)
'second year chap not partying' is the wordplay.
'second' becomes 's' (common abbreviation).
'year' becomes 'y'.
'partying' indicates anagramming the letters.
'chap'+'not'='chapnot'
'chapnot' anagrammed gives 'cophant'.
's'+'y'+'cophant'='SYCOPHANT'
(Other definitions for sycophant that I've seen before include "old informer" , "Austen's Mr Collins?" , "Crawler, toady" , "I'm obsequious" , "receiving ultimate in flattery from one such?" .)