Some cold, stern grandad, perhaps? (7)
I believe the answer is:
oldster
'grandad perhaps?' is the definition.
(a grandad might be an old person)
'some cold stern' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'OLDSTER' can be found hidden inside 'cold stern'.
(Other definitions for oldster that I've seen before include "A man getting old (colloq.)" , "One aged" , "Senior citizen (mainly US)" , "Person getting on" , "One no longer inexperienced" .)