Where tiny person is guarded by minute Rottweiler (2,5)
I believe the answer is:
in utero
'where tiny person is' is the definition.
'guarded by minute rottweiler' is the wordplay.
'guarded by' indicates the answer is hidden within the clue.
'IN UTERO' is hidden in the letters of 'minute rottweiler'.
(Other definitions for in utero that I've seen before include "Within the womb - routine (anag)" , "Where the foetus is" , "Before birth (Latin)" , "Before birth - routine (anag)" , "Pre-natal position (Latin)" .)