Hurrying away on purpose: it must be seen in perspective (9,5)
I believe the answer is:
vanishing point
'it must be seen in perspective' is the definition.
'hurrying away on purpose' is the wordplay.
'hurrying away' becomes 'vanishing'.
'on' is a charade indicator (letters next to each other).
'purpose' becomes 'point' (I've seen this before).
'vanishing'+'point'='VANISHING POINT'
(Other definitions for vanishing point that I've seen before include "Where parallel lines meet in perspective" , "Result of bluntness" , "It helps one maintain a proper perspective" , "One may see this in perspective" , "Indication of knife going in" .)