Meticulous in dress, old setters welcoming run out (8)
I believe the answer is:
rigorous
'meticulous' is the definition.
(thesaurus)
'dress old setters welcoming run out' is the wordplay.
'dress' becomes 'rig' (rig is a kind of dress**).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'setters' becomes 'us'.
'welcoming' means one lot of letters goes inside another (in sense of 'inviting in').
'run out' becomes 'ro' (cricket abbreviation).
'o'+'us'='ous'
'ous' enclosing 'ro' is 'orous'.
'rig'+'orous'='RIGOROUS'
'in' is the link.
(Other definitions for rigorous that I've seen before include "Demanding and stern" , "Unsparing" , "Allowing no deviation from a standard" , "Extremely thorough" , "Inflexible" .)