Girl in Resistance initially has trouble getting up (5)
I believe the answer is:
rhoda
'girl' is the definition.
'resistance initially has trouble getting up' is the wordplay.
'resistance' becomes 'r' (abbreviation).
'initially' suggests taking the first letters.
'trouble' becomes 'ado' (I've seen this before).
'getting up' is a reversal indicator.
The first letter of 'has' is 'h'.
'ado' back-to-front is 'oda'.
'r'+'h'+'oda'='RHODA'
'in' is the link.
(Other definitions for rhoda that I've seen before include "Girl" , "Girl's name; hoard (anag.)" , "Fem. name; hoard (anag.)" , "Woman" .)