Manage to follow shop's principal range (5)
I believe the answer is:
scope
'principal range' is the definition.
'scope' can be an answer for 'range' ('scope' can be a synonym of 'range'). I'm not certain of the 'principal' bit.
'manage to follow shop's' is the wordplay.
'manage' becomes 'cope' ('cope' can be a synonym of 'manage').
'to follow' says to put letters next to each other.
'shop's' becomes 's' (this might be a standard abbreviation of which I'm unaware).
'cope' after 's' is 'SCOPE'.
Can you help me to learn more?
(Other definitions for scope that I've seen before include "Range, compass" , "Range of view" , "Range; opportunity" , "Extent; viewer (colloq.)" , "Field" .)