Tube to deter travelling around? (7)
I believe the answer is:
tetrode
'tube' is the definition.
(type of tube in electronics)
'to deter travelling around?' is the wordplay.
'travelling around?' is an anagram indicator.
'to'+'deter'='todeter'
'todeter' is an anagram of 'TETRODE'.
(Other definitions for tetrode that I've seen before include "Type of valve" , "Radio valve" , "electronic apparatus" .)