A moralist with navy pants in charitable organisation (9,4)
I believe the answer is:
salvation army
'charitable organisation' is the definition.
'Salvation Army' can be an answer for 'organisation' (Salvation Army is an example). I'm unsure of the 'charitable' bit.
'a moralist with navy pants' is the wordplay.
'with' means one lot of letters go next to another.
'pants' indicates an anagram (UK informal term for 'nonsense' or 'rubbish').
'a'+'moralist'+'navy'='amoralistnavy'
'amoralistnavy' anagrammed gives 'SALVATION ARMY'.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for salvation army that I've seen before include "Christian body noted for social work and bands" , "Organisation founded by William Booth" , "Christian group" , "Charity" , "peaceful force" .)