Come across Republican not working after college (3,4)
I believe the answer is:
run into
'come across' is the definition.
('run into' can be a synonym of 'come across')
'republican not working after college' is the wordplay.
'republican' becomes 'r' (abbreviation).
'working' indicates anagramming the letters.
'after' says to put letters next to each other.
'college' becomes 'uni' (I've seen this in other clues**).
'not' with letters rearranged gives 'nto'.
'nto' put after 'uni' is 'uninto'.
'r'+'uninto'='RUN INTO'
(Other definitions for run into that I've seen before include "Meet accidentally on the trot?" , "Happen to meet - with a bump?" , "Meet (a person) by chance" , "Meet (someone) unexpectedly" , "charge?" .)