Beams thrown around by disheartened pilgrim outside upsetting knight (5)
I believe the answer is:
prism
'beams thrown around' is the definition.
I can't tell whether this defines the answer.
'disheartened pilgrim outside upsetting knight' is the wordplay.
'disheartened' means to remove the middle letters.
'outside' is an insertion indicator.
'upsetting' shows that the letters should be reversed in order.
'knight' becomes 'sir' (a knight has the title Sir).
'pilgrim' with its middle removed is 'pm'.
'sir' written backwards gives 'ris'.
'pm' placed around 'ris' is 'PRISM'.
'by' is the link.
Can you help me to learn more?
(Other definitions for prism that I've seen before include "Light-splitting glass" , "Prims (anag)" , "It breaks light up into rainbow's colours" , "Refracting glass" , "White light splitter" .)