Directive from senior Derryman (5)
I believe the answer is:
order
'directive' is the definition.
(I've seen this in another clue)
'from senior derryman' is the wordplay.
'from' indicates the answer is hidden within the clue.
'ORDER' is hidden within 'senior derryman'.
(Other definitions for order that I've seen before include "Enjoin in harmony" , "Command harmony" , "Instruct" , "association" , "Direct or requisition" .)