Pack up and post, perhaps (4)
I believe the answer is:
stop
'pack up' is the definition.
'stop' can be an answer for 'pack' (thesaurus). I am not certain of the 'up' bit.
'post perhaps' is the wordplay.
'perhaps' indicates an anagram.
'post' is an anagram of 'STOP'.
'and' acts as a link.
Can you help me to learn more?
(Other definitions for stop that I've seen before include "Come to a halt" , "Organ knob; get bus here" , "Withhold payment" , "colon, say" , "This watch is used to time races" .)