Scattered picadors regrouped (8)
I believe the answer is:
sporadic
'scattered' is the definition.
(similar in meaning)
'picadors regrouped' is the wordplay.
'regrouped' indicates an anagram (I've seen 'regroup' mean this (I've seen this in other clues)).
'picadors' anagrammed gives 'SPORADIC'.
(Other definitions for sporadic that I've seen before include "Occasional - intermittent" , "Occurring infrequently" , "Fitful, intermittent" , "Happening irregularly" , "Scattered - irregular" .)