Dealer in an organisation provides substance that will give them a little pep, perhaps (10)
I believe the answer is:
adrenaline
'substance that will give them a little pep perhaps' is the definition.
'adrenaline' can be an answer for 'substance' (adrenaline is a kind of substance). I'm not certain of the remainder of the definition.
'dealer in an organisation' is the wordplay.
'organisation' indicates an anagram.
'dealer'+'in'+'an'='dealerinan'
'dealerinan' anagrammed gives 'ADRENALINE'.
'provides' is the link.
Can you help me to learn more?
(Other definitions for adrenaline that I've seen before include "Stimulating hormone" , "It stimulates" , "Hormone replacement" .)