To portray text is extremely difficult without a big budget movie (6)
I believe the answer is:
depict
'to portray' is the definition.
('depict' can be a synonym of 'portray')
'extremely difficult without a big budget movie' is the wordplay.
'extremely' means to remove the middle letters (only the extremes of the word are used).
'without' means one lot of letters goes inside another ('without' can be similar in meaning to 'outside').
'a big budget movie' becomes 'epic' (epic film).
'difficult' with its centre removed is 'dt'.
'dt' placed around 'epic' is 'DEPICT'.
'text is' is the 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 depict that I've seen before include "Represent visually" , "Paint" , "Show, illustrate" , "Make a likeness of" , "Represent in drawing or painting" .)