This is a cross-reference clue - the definition and/or wordplay is found by looking at another clue in the puzzle (clue 22 in this case).
You need to look at clue 22 in the crossword to understand what this clue is asking for. The answer FOLD will be defined or constructed based on what clue 22 says.
Answer: FOLD | This is a cross-reference where clue 22 provides the definition and/or wordplay needed to arrive at FOLD. Without seeing clue 22, the specific parsing cannot be determined.