### Clue: What to wear, that is, in holes likely to contain water (7)
### Answer: WELLIES 
 ### Explanation: Definition: What to wear, that is, in holes likely to contain water
 IE(abbrev. of "id est";that is) **contained in**(in) WELLS(holes likely to contain water).
Answer: Waterproof boots to wear in wet or muddy conditions found in, eg. a waterfilled hole. A nice WIWD (wordplay intertwined with defn.) clue.