Urging clothing that's uncomfortable: red pants in bigshot's style (5,8)
I believe the answer is:
power dressing
'bigshot's style' is the definition.
'urging clothing that's uncomfortable red pants' is the wordplay.
'urging' becomes 'pressing' ('press' can be a synonym of 'urge'**).
'clothing' means one lot of letters goes inside another.
'that's uncomfortable' becomes 'ow'.
'pants' indicates anagramming the letters (UK informal term for 'nonsense' or 'rubbish').
'red' is an anagram of 'erd'.
'ow'+'erd'='owerd'
'pressing' placed around 'owerd' is 'POWER DRESSING'.
'in' is the link.
(Other definitions for power dressing that I've seen before include "what some businesswomen adopt" , "Style perhaps adopted by women executives" , "(Of women) donning clothes to look authoritative" , "Wearing of clothes designed to give an impression of authority" , "Female fashion style designed to give an impression of confidence and efficiency" .)