Choose short, ordinary thread primarily for embroidered loop (5)
I believe the answer is:
picot
'loop' is the definition.
(I have seen 'Decorative loop' mean 'picot' so perhaps 'loop' could also mean 'picot')
'choose short ordinary thread primarily for embroidered' is the wordplay.
'short' suggests taking the first letters.
'primarily' says to take the initial letters.
'for' is a charade indicator (letters next to each other) (I've seen this in other clues).
'embroidered' becomes 'pi' (I can't justify this - if you can you should believe this answer much more).
The initial letter of 'choose' is 'c'.
The first letters of 'ordinary thread' is 'ot'.
'c'+'ot'='cot'
'cot' after 'pi' is 'PICOT'.
Can you help me to learn more?
(Other definitions for picot that I've seen before include "Loopy series" , "Pattern of small loops, as in lace" , "Lace pattern of hoops" , "Embroidery stitch - topic (anag)" , "sequence of loops" .)