Fancy catalogues seen partially (5)
I believe the answer is:
guess
'fancy' is the definition.
(I've seen this before)
'catalogues seen partially' is the wordplay.
'partially' indicates a hidden word.
'GUESS' is hidden in the letters of 'catalogues seen'.
(Other definitions for guess that I've seen before include "Estimate roughly" , "Estimate; suppose" , "Take a stab at the answer" , "Divine - estimate" , "Hypothesis" .)