### Clue: Growth of power with steel tower mostly erected (5)
### Answer: POLYP 
 ### Explanation: Definition: Growth
 P(symbol for "power" in physics) **plus**(with) **reversal of**(… erected, in a down clue) "pylon"(a steel tower carrying electricity cables high above ground) **minus its last letter**(mostly).
Defn: An abnormal tissue ….