Travel firm's head of marketing's silent (7)
I believe the answer is:
commute
'travel' is the definition.
(I know that commute is a more specific form of the action the travel)
'firm's head of marketing's silent' is the wordplay.
'firm' becomes 'co' (a firm is a company).
'head of' suggests taking the first letters.
'silent' becomes 'mute' (synonyms).
The first letter of 'marketings' is 'm'.
'co'+'m'+'mute'='COMMUTE'
(Other definitions for commute that I've seen before include "Travel some distance to and from work" , "Travel daily to work; mitigate" , "Exchange - travel to work" , "To reduce severity of the punishment" , "Travel into the city to work" .)