Safeguard space and get positive (6)
I believe the answer is:
ensure
'safeguard' is the definition.
(I've seen this in another clue)
'space and get positive' is the wordplay.
'space' becomes 'en' (in printing, a space as wide as a letter 'n').
'and get' is a charade indicator (letters next to each other).
'positive' becomes 'sure' (similar in meaning).
'en'+'sure'='ENSURE'
(Other definitions for ensure that I've seen before include "Make certain (something will occur)" , "Make certain that (something occurs)" , "Make certain, confirm" , "Make certain, secure" , "Guarantee" .)