Beloved certain to be in step (9)
I believe the answer is:
treasured
'beloved' is the definition.
(thesaurus)
'certain to be in step' is the wordplay.
'certain' becomes 'sure' ('sure' can be a synonym of 'certain').
'to be in' means one lot of letters goes inside another.
'step' becomes 'tread' ('tread' can be a synonym of 'step'**).
'sure' placed into 'tread' is 'TREASURED'.
(Other definitions for treasured that I've seen before include "Chersihed, held dear" , "Regarded as precious" , "Loved" , "Valuable" , "Valued" .)