Relentless old men with capacity to follow batting? (10)
I believe the answer is:
inexorable
'relentless' is the definition.
('inexorable' can be a synonym of 'relentless')
'old men with capacity to follow batting?' is the wordplay.
'old' becomes 'ex'.
'men' becomes 'or' (I've seen this in other clues).
'with capacity' becomes 'able'.
'to follow' means one lot of letters go next to another.
'batting?' becomes 'in'.
'ex'+'or'+'able'='exorable'
'exorable' put after 'in' is 'INEXORABLE'.
(Other definitions for inexorable that I've seen before include "Harsh" , "Inescapable" , "Unstoppable" , "Relentless" , "Unrelenting" .)