Surpass old-fashioned tourists finally on excursion (8)
I believe the answer is:
outstrip
'surpass' is the definition.
(I know that surpass can be written as outstrip)
'old-fashioned tourists finally on excursion' is the wordplay.
'old-fashioned' becomes 'out' (as opposed to 'in').
'finally' says to take the final letters.
'on' means one lot of letters go next to another.
'excursion' becomes 'trip' (I've seen this before).
The last letter of 'tourists' is 's'.
'out'+'s'+'trip'='OUTSTRIP'
(Other definitions for outstrip that I've seen before include "Surpass, overtake" , "As to purist, surpass or run faster" , "eclipse" , "Leave behind" , "Move faster than and overtake" .)