A saint always will provide guidance (5)
I believe the answer is:
'provide guidance' is the definition.
(I've seen this in another clue)
'a saint always' is the wordplay.
'a saint' becomes 'st' (abbreviation).
'always' becomes 'eer' (poetic way of saying ever).
'will' is the link.
(Other definitions for steer that I've seen before include "cox" , "bovine individual?" , "piece of advice" , "Drive - young ox" , "Direct; young ox" .)