Impractical type with twitch (8)
I believe the answer is:
romantic
'impractical' is the definition.
('romantic' can be similar in meaning to 'impractical')
'type with twitch' is the wordplay.
'type' becomes 'roman' (variety of type eg Times New Roman).
'with' means one lot of letters go next to another.
'twitch' becomes 'tic' (tic is a kind of twitch).
'roman'+'tic'='ROMANTIC'
(Other definitions for romantic that I've seen before include "Amatory" , "Imaginative or amorous" , "Inclined to love" , "Amorous (but not practical?)" , "Literary period in early 19th century" .)