One wanting great precision in line in display material (8)
I believe the answer is:
stickler
'one wanting great precision' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'line in display material' is the wordplay.
I cannot really understand how this works, but
'line' could be 'l' (used when specifying particular lines from a poem) and 'l' is located in the answer.
The remaining letters 'sticker' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'in' acts as a link.
Can you help me to learn more?
(Other definitions for stickler that I've seen before include "One's less than flexible" , "Fusspot" , "Particular type" , "Purist" , "One who insists on something, like punctuality" .)