Guide sister around part of golf course (5)
I believe the answer is:
steer
'guide' is the definition.
(synonyms)
'sister around part of golf course' is the wordplay.
'sister' becomes 'sr' (abbreviation as in names of nuns).
'around' means one lot of letters goes inside another.
'part of golf course' becomes 'tee' ('tee' is part of 'golf course').
'sr' going around 'tee' is 'STEER'.
(Other definitions for steer that I've seen before include "Handle" , "beef producer" , "The animal to direct" , "Reset so as to direct" , "Direct movement" .)