By getting out of line, you want support (4)
I believe the answer is:
pier
'want support' is the definition.
'pier' can be an answer for 'support' (type of structure). I'm unsure of the 'want' bit.
'by getting out of line' is the wordplay.
'by' becomes 'per' (I've seen this in another clue).
'getting' indicates putting letters inside.
'out of line' becomes 'i' (I can't justify this - if you can you should believe this answer much more).
'per' going around 'i' is 'PIER'.
'you' acts as a link.
Can you help me to learn more?
(Other definitions for pier that I've seen before include "Seaside resort feature" , "Seaside structure" , "Break-water or landing stage" , "Coastal platform" , "Mole, wall between windows" .)