Short introduction to crosswords is found in Chapter 1 (7)
I believe the answer is:
concise
'short' is the definition.
('concise' can be similar in meaning to 'short')
'introduction to crosswords is found in chapter 1' is the wordplay.
'introduction to' says to take the initial letters (I've seen 'introductions to' mean this).
'found in' is an insertion indicator.
'chapter' becomes 'c'.
'1' becomes 'one' ('one' can be a synonym of '1').
The initial letter of 'crosswords' is 'c'.
'c'+'is'='cis'
'c'+'one'='cone'
'cis' inserted into 'cone' is 'CONCISE'.
(Other definitions for concise that I've seen before include "Compact - brief" , "Brief and to the point" , "Short and clear" , "Short and brief" , "Terse" .)