Meticulous short prickly type takes head off Rocky (8)
I believe the answer is:
thorough
'meticulous' is the definition.
(thesaurus)
'short prickly type takes head off rocky' is the wordplay.
'short' means to remove the last letter.
'prickly type' becomes 'thorn' (I've seen this before).
'takes head off' means to remove the first letter (I've seen 'taking head off' mean this).
'rocky' becomes 'tough' ('tough' can be a synonym of 'rocky').
'thorn' with its last letter taken off is 'thor'.
'tough' with its first letter taken away is 'ough'.
'thor'+'ough'='THOROUGH'
(Other definitions for thorough that I've seen before include "Assiduous, painstaking" , "Painstakingly careful and accurate" , "Complete - painstaking - unqualified" , "Detailed" , "Not superficial or partial" .)