Moving supply of things for reading by ambassador (5)
I believe the answer is:
lithe
'moving supply' is the definition.
(I've seen this in another clue)
'reading by ambassador' is the wordplay.
'reading' becomes 'lit' (abbreviation for literature).
'by' says to put letters next to each other.
'ambassador' becomes 'HE' (His or Her Excellency).
'lit'+'he'='LITHE'
'of things for' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for lithe that I've seen before include "showing flexibility" , "Elastic" , "Of body, flexible and supple" , "Physically supple, agile" , "quick to move" .)