Mobile phone with more influential output? (9)
I believe the answer is:
pheromone
'influential output?' is the definition.
(pheromones are outputs that have influence)
'mobile phone with more' is the wordplay.
'mobile' indicates an anagram.
'with' says to put letters next to each other.
'phone'+'more'='phonemore'
'phonemore' is an anagram of 'PHEROMONE'.
(Other definitions for pheromone that I've seen before include "Chemical affecting behaviour" , "Chemical signal between organisms" , "What attracts" , "Substance secreted that affects others of same species" , "Chemical attractor" .)